Final Washington DC MS4 Stormwater Discharge Permit

US EPA has released the final stormwater discharge permit for the Washington DC area municipal separate storm sewer system (“Washington DC MS4 Permit”). The Washington DC MS4 Permit included a number of performance-based requirements, including:

• Requiring a minimum of 350,000 square feet of green roofs on District properties;


• Planting at least 4,150 trees annually and developing a green landscaping incentives program;


• Retaining 1.2 inches of stormwater on-site from a 24-hour storm for all development projects of at least 5,000 square feet;


• Developing a stormwater retrofit strategy, and implementing retrofits over 18 million square feet of drainage of impervious surfaces;


• Developing consolidated implementation plans for restoring the impaired waterways of the Anacostia and Potomac Rivers, Rock Creek, and the Chesapeake Bay; and


• Preventing more than 103,000 pounds of trash annually from being discharged to the Anacostia River.

EPA believed the new permit conditions were necessary because impervious surfaces in the District, such as roads, rooftops and parking lots, channel stormwater directly into local streams and rivers. Improperly managed stormwater runoff from the District damages streams, causes significant erosion, and carries excessive pollutants like nitrogen, phosphorus, sediment, toxic metals, and solvents downstream and into the Chesapeake Bay. The permit aids the District in meeting its Chesapeake Bay pollution reduction targets and its Watershed Implementation Plan.

Caltha LLP provides expert consulting services to public and private sector clients nationwide to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

For further information contact Caltha LLP atinfo@calthacompany.com or Caltha LLP Website